Electronic Dice Circuit

An electronic dice is a classic first project for those getting interested in electronics. A timer, counter and a few LEDs makes a circuit that can also add a new twist to some old boring board games. When the switch is pressed, a 555 timer in astable mode pulses a BCD counter which lights up a series of LEDs wired to mimic a dice. Two AND gates are used to reset the count back to one whenever the BCD output is seven. Thus, the circuit is not truly random but the natural bounce present in a pushbutton and the normal human ability to operate much slower then the oscillator make the output of the circuit seem random.

Schematic

Parts

Part

Total Qty.

Description

Substitutions

R1, R5, R6

3

22K 1/4W Resistor

R2

1

10K 1/4W Resistor

R3

1

4.7K 1/4W Resistor

R4

1

150K 1/4W Resistor

R7 - R13

7

330 Ohm 1/4W Resistor

C1

1

1uF Electrolytic Capacitor

C2

1

4.7uF Electrolytic Capacitor

D1

1

1N4148 Signal Diode

D2 - D8

7

Red/Green/Yellow LED

Q1

1

2N3904 NPN Transistor

U1

1

555 Timer IC

U2

1

74LS192 4 Bit Counter IC

U3

1

74LS08 Quad Intengreted AND Gate IC

S1

1

SPST Momentary Pushbutton Switch

MISC

1

Board, Wire, Sockets For ICs, Case

Notes

Pushing and holding S1 causes the LEDs to rapidly cycle. Releasing the button locks the pattern and shows a number from 1 to 6.

When building the circuit, make sure to position the LEDs as shown on the schematic. Otherwise the pattern of the dice will look weird.

Two circuits can of course be both powered by one switch to make a dual dice.

I believe that the pin 7 on IC LS192 that is pulled to VCC should be left open and pin 15 should be set to VCC instead. Please note that pin 7 is an output and that Pin 15 is the least significant input digit.

Dear Anonymous of Monday, May 03, 2010.
Is that a question. Well, if you look at the diagram, it says he is using 5v, so any capacitor of 6v an more is adequate. Just make sure you have a regulated 5v power supply.
for anonymous saturday, september 26, 2009. Obviously not enough! I have bought them many times over on eBay, nice and safely using paypal! yes, it is that easy. You register with paypal, using either your bank account (dependant on country) or a credit / debit card. Simple.

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